Filter pad



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Dec. 7, 1937. A. w. FRANzMEn-:R 2,101,811

FILTER PAD Filed De-C. 28, 1935 2 Sheets-Sheet l Dec. 7, 1937. A W, FRANZMEIER 2,101,811

FILTER PAD Filed Dep. 28, 1935 2 Sheets-Sheet 2 atented Dec. 7,. 1937 UNITED STATES PATENT oFFlcE l FILTER PAD Alvin W. Franxmeler, Rosemount, Minn.

Application'December 28, 1935, Serial No. 56,509

6 Claims.

My invention relates to an improvement in iilter pads. It is the primary purpose of this invention to provide a filter pad which will strain thoroughly and quickly, and which will not wash even when subjected to a considerable force of liquid tending to part the fibres or tlssuesforniing the pad.

Attempts have been made for some time to provide a satisfactory pad which will strain faster 10 than a cotton pad, and yet which will not wash as readily as will such a cotton pad.A I have made extended experiments with material in the nature of soft absorbent paper. Unless a strainer is very carefully designed to avoid a strong iiow of liquid in any one direction, however,

` such material will wash away in spots, permitting liquid not properly strained to iiow therethrough. This material also, in some forms, has the property of swelling up somewhat, when moistened,

zo spreading the fibres apart and making the pad less eilicient as a straining element.

It is an object of my invention to take advantage of these properties which have previously seemed detrimental, and to form a pad which will be extremely effective, and which yet will strain more quickly than is ordinarily possible.

This aim I accomplish by strengthening the material forming the pad by some means so that -Y the washing tendency is overcome, and so that i the lower portion of the pad is held firmly so that it may not swell suiliciently to allowforeign matter to pass through the filter pad. The top portion of the pad preferahlyis allowed Vto swell? so that this portion is especially capable of stopping the larger particles of foreign matter, allowing the smaller particles to pass through this portion to be stopped by the lower portion of the pad. I have vfound that, as a result, the liquid passes cleanly through the lter more quickly 4o than is possible with the common type of pad.

It is also a feature off my invention to provide a means of stiffening the pad, so that it may be handled more readily, and so that it will require leas support from the bottom when in straining position. By the use of this stiifening means, I have found it to be often practical to use the filter pad supported onlyl along its edges, and entirely unsupported beneath its straining area. Such use is of course of great importance, for every type of supporting means beneath the strainer pad reduces the effective area ofthe pad, and slows the straining action.

I have further found that the use of a fibrous material such as loosely formed, absorbent paper, usedin combination with a thin sheet of material (C1. 2li-169) such as cotton, is superior to a pad formed of cotton alone, in a thicker sheet, for if the material such as paper is combined as a layer above the cotton, it acts to strain out the larger particles before the liquid reaches the cotton. The 5 liquid accordingly will pass through such a pad quickly, for the foreign matter is distributed more widely through the entire thickness of the pad, rather than in a single layer on the top of the Pad. 10

It is my purpose to stiifen the filter pad by means of pressing the material to form a relatively stiff rib or series of ribs, or to provide a row of stitching for this purpose, or by pressing grooves in the paper which may be filled with a 15 reinforcing material which will harden and hold the pad sti. This reinforcing material could also be applied on the surface of the pad.

These and other objects and novel features of my invention will be more fully and clearly set forth in the accompanying specification and claims. A

In the Vdrawings forming a part of the specilisation:

Figure 1 is a perspective view of a portion of 25 my pad, the various layers thereof being broken away so that the 'construction may be noted.

Figure 2 is a cross-sectional view of the pad shown in Figure l. l l

3 is a cross-sectional view of a pad 80 identical with that of Figure 2, except that no lower gauze reinforcing is provided.

Figure 4 is a cross-sectional view of a small portion of an alternative type of pad, showing stitching extending therethrough. 35

Figure 5 is a cross-sectional view of a type of pad construction similar to that shown in Figure 4, but having reinforcing gauze on the top and bottom thereof to better support the stitching extending therethrough. o

Figure 6 illustrates a pad formed of fibrous material and gauze, before this material is pressed.

Figure '7 illustrates the pad of Figure 6, after pressing the material into the gauze, and after adding unpressed fibrous material on the top of 45 the pressed portion.

Figure 8 is a perspective view of a portion of a pad made of two separately pressed portions superimposed. v

Figure 9 is a view similar to that of Figure 8, 50 in which the pad is not reinforced by gauze.

Hy pad A, as formed in Figures 1 and 2, is built up of an upper layer of brous material, such as soft paper of a type capable of absorbing water and of permitting liquid to pass there- 55 through while retaining foreign matter carried thereby. This upper layer Il of fibrous material is preferably pressed into a layer of gauze so as to be partially embedded directly into the gauze. As shown, the upper layer I3 is pressed along narrow areas II, forcing the ilbrous material down into the gauze layer I2 to hold these ma; terials closely united. The pressed areas are sufficiently close together to firmly hold the fibrous layer III to the gauze I2 when liquid is applied.

Beneath the gauze I2 are provided several layers I3 of brous material, which may be of the same nature as the upper layer III. These layers I3 are further reinforced by a gauze layer I4 extending underneath the pad.

With this type of pad, it appears that the upper layer I0 swells up somewhat when the liquid to be strained is poured over the same. Ihis spreads the bres forming the layer farther apart, and allows some of the smaller particles of material to pass therethrough, through the gauze I2, to the lower layers I3.

The lower layers I 3 are prevented from swelling to any great extent by the layer of gauze I2. The weight of the liquid being strained seems to urge the gauze down against the layers I3, preventing the layers I3 from swelling materially and preventing the bres therein from spreading greatly. The layers I3 thus catch the smaller particles of foreign material in the liquid and thoroughly cleanse the material.

If desired, the material forming the layers I3 may be of libres which pack together more readily than those of the layer I0. It is important, however, to avoid the use of materials which pack too tightly, to maintain the desired flow through the strainer pad.

In Figure 2 I illustrate filling mate'rial used for reinforcing purposesin the pressed portions of the pad. The filling material I5 is of such material as casein or other material which is flexible to a certain extent so that it willnot cracki l over the surface of any of the layers of the pad,

and need not be in the pressed portions of the pad as shown. The illustrated form, however, has the advantage of being more firmly held in place, and of presenting a -virtually smooth upper surface to the pad, as well as the advantage of providing a strengthening rib extending down into the body of the pad.

The pad A illustrated in Figure 3, is similar to that shown in Figures 1 and 2, without the layer of gauze on the bottom of the pad. It will be noted that in the illustrated forms, Figure 2 shows merely the top layer of material I0 pressed into the gauzel2 before the layers I3 are applied. 'I'he same procedure can be followed, however, by applying the layers I3 before the pressing operation, as shown in Figure 3, so that the layers I3 are pressed somewhat into the layer of gauze I2 as well as the layer Il).

In place of pressing the material along spaced lines as shown in Figure 1, 2, and 3, the pads B and B', shown in Figures 4 and 5 of the drawings, are stitched along parallel lines, by some such means as a gang sewing machine. This provides rows I6 of stitching extending through the entire pads B and B'. The pad B is comprised of an upper layer Il, a gauze layer Il, and

lower layers Il of straining material. The pad B. shown in Figure 5, is made up of two sheets of gauze, 2l and 22, between which are interposed layers 23 of straining material. These forms are illustrative of constructions suitable for the purpose. 0bviously, other forms of constructions could be used without changing the invention.

Figures 6 and 7 show a slightly diiferent construction, or a slightly modified form of pad. In 10 this construction, two layers 24 of absorbent mav terial, such as loosely formed absorbent paper are placed on a sheet of gauze 25, as shown in Figure 6, and then pressed over the entire surface. This acts to p ress the paperdown into the gauze, i5

making a substantially integral layer which is relatively stiff and which is suiilciently flexible to prevent cracking when bent. The pad is completed by adding unpressed layers of material 24' over the sheet thus formed,as shown in Figure 7. 20 It may be seen that this construction is very I similar to that shown in Figures 1, 2, and 3,but that the order of the elements is changed somewhat, and one of the straining layers, or more,

is entirely pressed into the gauze layer. Care 25 must be taken in forming this type of Apad C to avoid pressing the straining material into the gauze so firmly that the straining action is seriously impeded. i'

The pad D, shown in Figure 8, comprises two 30 units such as were shown in Figures 1 to 3, arranged so that the pressed or reinforced portions of the pad are at angles one with the other. For example, each unit of the pad D comprises a straining element portion 26 and a gauze layer 2l 35 into which the layer 26 is pressed along parallel Y Y lines 28 and parallel lines 29, which intersect each other at right angles, or substantially so. The upper unit 30 however, has its lines 28 and 23,.'

running parallel with the edges of the pad shown, 40

while the lower unit 32 is shown with the pressed portions running diagonally. This provides added strength and thoroughly reinforces the pad D.

The pad D' shown in Figure 9 is similar to the pad -D, but contains no gauze layers. The vari- 45 ous layers 33 forming the pad are pressed in the manner described in connection with the pad D, the compressing of the material atvthesgpoints acting to reinforce the pads. The ulad" 'R 35 along which the upper unit 33 is pressed 50 extend angularly with respect to the lines 31 and 38 along which the lower unit 33 is pressed.

VYas shownirrFigureil.;

I have found that pads made in accordance with my invention are sufficiently stiff to require 55 little or no support beneath the same during the straining action. They are very quick in action, and permit a large quantity of liquid to be strained in a short period of time. Regardless of this fact, they are eilicient and strain the liquid o thoroughly. Furthermore, because of the fact that the upper portion of the pad usually acts to remove the larger impurities, and the inter-k mediate portions serve to obstruct the smaller impurities, pads made in this manner can be 65 used longer than pads which are more closely matted together on top and which form a layer of impurities quickly over the entire top surface.

In accordance with the patent statutes, I have described the principles of operation of my 70 strainer pads, and while I have endeavored to set forth the best embodiments thereof, I desire to have it understood that this is only illustrative of a means of carrying out my invention, and that obvious changes could be made within the scope 75 of the following 'claims without the spirit ot the invention.

I claim: A

l. A strainer pad comprising a layer of gauze, and a layer of filtering material free from said gauze through the greater area thereof, said ltering material extending into said gauze at spaced intervals to reinforce the pad.

2. A strainer pad comprising, two integral units, each unit including a strip of gauze and a sheet of soft ltering material pressed into said gauze along parallel lines, thelines of one of said units crossing the lines oi the other of said units in the complete pad.

3. A strainer pad comprising, two integral portions, each portion including a strip of gauze and a layer of soft filtering material pressed into said gauze along right angularly disposed lines, the lines of one of said units crossing the lines of the other of said units in said pad.

4. A strainer pad comprising a thickness of departing from straining material of relatively low tensile strength, and a reinforcing means for said material, said reinforcing means comprising strips of exible material of'- relatively higher tensile strength, said strips being adhered to a surface of said material.

5. A strainer pad comprising a thickness of straining material of relatively low 'tensile strength, and a reinforcing means for said material, said reinforcing means comprising strips of flexible adhesive material of relatively higher tensile strength adhered to a surface of said straining material.

' 6. A strainer pad comprising a thickness of straining material of relatively low tensile strength, and a reinforcing means for said material, said reinforcing means comprising strips of exible adhesive material of relatively higher tensile strength adhered to, and partially embedded in, said straining material.

ALVIN W. 

